CN107888024A - Cooling system - Google Patents

Abstract

The invention relates to a cooling system (28) for an electric machine comprising a drive shaft (26) and a rotor shaft (2) of a rotor (4), the cooling system (28) comprising a first bushing (13a) and The second sleeve (13b), wherein the first sleeve (13a) coaxially surrounds the drive shaft (26), the second sleeve (13b) coaxially surrounds the first sleeve (13a), and the first sleeve (13a) coaxially surrounds the first sleeve (13a). 13a) and the second sleeve (13b) define a first flow space (14) for the cooling medium, the rotor shaft (2) coaxially surrounds the second sleeve (13b), the second sleeve (13b) and the rotor The shaft (2) defines a second flow space (6) for a cooling medium.

Description

cooling system

technical field

The invention relates to a cooling system for an electric machine and to an electric machine.

Background technique

An electric machine has, for example, a component called a rotor, which turns during its operation. Due to this component, and due to the current flowing through the electrical conductors of the electrical machine, the electrical machine may become hot. But it is possible to cool the motor through the cooling system.

Laid-open document DE 10 2013 104 711 A1 describes an electric machine with a rotor shaft and a device for cooling the rotor shaft, wherein the rotor shaft is designed as a hollow shaft. It is proposed here that the cooling device has a stationary cooling lance which passes axially through the hollow shaft. The cooling lance has an inlet and an outlet for the cooling medium and a cooling channel connected to the inlet and the outlet, which passes axially through the cooling lance.

Laid-open document EP 0 660 492 A1 describes a cooling system for an electric motor with a gearbox, a liquid internally cooled but hollow rotor shaft for the electric motor and an externally cooled stator. The cooling system has a shaft cooling structure, which enables a high degree of utilization of the electric machine and can also be used for a packaged and thus noise-reduced electric machine.

Furthermore, a rotary electric machine with a cooled hollow rotor shaft is known from the publication EP 1 168 572 A2.

Contents of the invention

Against this background, the object of the invention is to improve the cooling system of an electric machine.

This object is achieved with a cooling system and an electric machine having the features of the independent claims. Embodiments of the cooling system and the electric machine emerge from the dependent claims and the description.

The cooling system according to the invention is provided for cooling an electric machine with a rotor shaft for driving a transmission shaft of an external device and a rotor of the electric machine. The cooling system has at least one first sleeve and at least one second sleeve as components, wherein the first sleeve surrounds the transmission shaft coaxially, and the second sleeve surrounds the first sleeve coaxially. The first sleeve and the second sleeve define a first flow space for a cooling medium. Furthermore, the rotor shaft coaxially surrounds or delimits a second sleeve, the second sleeve and the rotor shaft delimiting or enclosing a second flow space for the cooling medium. The second sleeve is designed to separate the first flow space from the second flow space of the cooling system.

A cooling system is usually provided for an electric machine which has a housing, wherein the drive shaft and the rotor shaft are rotatable relative to the housing. The two bushings of the cooling system are fixedly connected to the housing and are thus fastened to the housing. During operation of the electric machine and/or the cooling system, the drive shaft rotates in the first sleeve at the speed of the device to be driven, and the rotor shaft rotates around the second sleeve at the speed of the rotor.

It is proposed here that the transmission shaft, the two bushings and the rotor shaft are designed as columns or cylinders and have a common axis of symmetry.

In one embodiment, the first of the two flow channels can or will be used as a supply route for the cooling medium, the second of the two flow channels can or will be used as the Media return route. During operation of the cooling system it is provided that the cooling medium flows or is conveyed through the supply line in a first, axially directed direction. The cooling medium then flows in radial direction from the supply line to the return line or is conveyed in radial direction. Furthermore, it is proposed that the cooling medium flows or is conveyed through the return line in a second, axially directed direction, which is opposite to the first, axially directed direction. In this case, a stationary liquid column of the cooling medium is obtained in one of two directions, usually in the first direction, when the cooling medium flows in the supply line between the two stationary/fixed sleeves. If the cooling medium flows in the opposite direction in the return path, the liquid column also rotates due to the rotation of the axis of rotation.

The two flow regions are connected to one another via and/or via a transition region, wherein the cooling medium can flow or be conveyed in radial direction through the transition region.

In one embodiment, the flow space designed as a return line coaxially surrounds the flow space designed as a supply line, wherein a stationary flow of the cooling medium results in the supply line between the two stationary sleeves. A liquid column, a rotating liquid column is obtained in the return path between the stationary second sleeve and the rotating rotor shaft.

The electric machine according to the invention has an embodiment of the rotor shaft, the transmission shaft and the cooling system.

In this case, the rotor shaft surrounds the drive shaft coaxially, wherein components of the cooling system, at least the bushing, are arranged between the drive shaft and the rotor shaft.

The rotor shaft, as the carrier of the rotor, is designed to rotate the rotor relative to the stator at the rotational speed of the electric machine. The drive shaft is designed to rotate at the speed of the external device for driving the external device. In this case, the two rotational speeds are distinguished by a rotational speed difference.

With the proposed cooling system surrounded by the rotor shaft, it is possible to cool the rotor shaft without cavitation.

In the electric machine, the hollow rotor shaft surrounds the drive shaft of the electric machine, which can also be designed and/or referred to as a flange shaft. In this case, the rotor shaft can be cooled on an inner profile of the rotor shaft which, as an outer wall, delimits a second flow space for the cooling medium. The inlet on the supply line and the outlet on the return line are arranged between the drive shaft and the rotor shaft and thus on the first side of the electric machine, while the transition area between the supply line and the return line is arranged on the drive shaft and on the second side of the rotor shaft and thus the electrical machine opposite the first side. In this case, the cooling medium can flow through the supply line and the return line axially in opposite directions. Even at high rotational speeds of more than 5000 revolutions per minute, cooling of the rotor shaft and thus of the rotor rotating with the rotor shaft can be ensured, while the cooling medium can flow through the cooling system without cavitation.

In this case, the cooling medium flows between the two stationary or stationary and cylindrical sleeves of the cooling jacket, which delimit and/or delimit a generally configured supply path. The flow space and the inlet of the flow space are delimited, the inlet having the smallest possible cross-section and thus requiring only a small installation space. Inside the supply line, the cooling medium forms an axial liquid column. In the flow region designed as a return flow path, the cooling medium is rotated due to the rotor shaft, which delimits the return flow path as a second flow region and forms the outer wall of this second flow region. Thus a rotating column of liquid is formed. A radial or rotational flow portion of the cooling medium is thus formed only on the inner profile of the rotor shaft.

A cooling system arranged coaxially between the transmission shaft and the rotary shaft can thus be used for cooling measures, which cooling system also forms the interior space and/or core of the rotary shaft.

The electric machine also has a stator, wherein the rotor is rotatable relative to the stator. In the generator mode of operation of the electric machine, mechanical energy is converted into electrical energy, and in the mode of operation of the electric motor, electrical energy is converted into mechanical energy.

As part of the cooling system, two stationary bushings are used between the drive shaft or flange shaft and the rotor shaft, wherein the two stationary bushings are arranged on the central axis of the rotor shaft and the drive shaft, ie the axis of symmetry or outside the axis of rotation. In contrast to the prior art, it is thus possible to dispense with the cooling lance which is generally arranged in the center of the axis of the shaft.

Furthermore, the drive shaft or the flange shaft arranged inside the first bushing is sealed against the cooling medium, for example water or oil.

During motor operation, the rotor arranged on the rotor shaft rotates relative to the stator at the motor speed. In contrast, the drive shaft, which is arranged within the rotor shaft and the cooling system, rotates at the speed of an external device to be driven by the drive shaft, for example a wheel, which may be designed as part of a motor vehicle. The gap between the drive shaft or the flange shaft and the rotor shaft is used for cooling the rotor shaft by means of a stationary or fixed sleeve, wherein the cooling medium can flow without cavitation.

Further advantages and embodiments of the invention emerge from the description and drawings.

The features mentioned above and those to be explained below can of course be used not only in the respectively specified combination, but also in other combinations or alone without departing from the scope of the present invention.

Description of drawings

The invention is schematically illustrated with the aid of an embodiment in the drawing and is described in more detail by way of example and with reference to the drawing.

FIG. 1 shows a schematic diagram of details of an embodiment of an electric machine according to the invention with an embodiment of the cooling system according to the invention.

Detailed ways

The details of the electric machine schematically shown in FIG. 1 comprise: a cylindrical rotor shaft 2 for the rotor 4 ; a first flow space 14 designed as a supply path for a fluid cooling medium; two bearings 8 ; housing 10 ; cooling sleeve 12 arranged stationary or stationary on housing 10 , comprising two cylindrical sleeves 13 a , 13 b for cooling; second flow space designed as return flow path 6 ; a first seal 18 ; at least one bearing 20 for the cooling jacket 12 ; a transition region 22 between the two flow spaces 6 , 14 ; a second seal 24 and a cylindrical drive shaft 26 .

During motor operation, the rotor 4 rotates at the rotational speed of the motor relative to the stator (not further shown). The drive shaft 26 is designed to drive an external device, here for example a wheel for driving or advancing the motor vehicle, wherein the drive shaft 26 rotates at the speed of the external device, here the wheel.

Furthermore, the rotor shaft 2 and the drive shaft 26 are connected to one another via a transmission, not shown in any further detail here. In this case, the transmission is flanged laterally to the rotor shaft 2 and the drive shaft 26 . The rotor shaft 2 and the transmission shaft 26 can thus rotate simultaneously during operation at different rotational speeds which are distinguished by rotational speed differences.

Here, the drive shaft 26 is coaxially surrounded by a first flow space 14 designed as a supply line, which is in turn coaxially surrounded by a second flow space 6 designed as a return line, which is surrounded by The rotor shaft 2 of the rotor 4 surrounds it coaxially. At least the two flow spaces 6 , 14 and the transition region 22 connecting the two flow spaces 6 , 14 are part of a cooling system 28 according to the invention and are used for conveying a cooling medium.

During operation of the cooling system 28 , the cooling medium flows axially or in the axial direction into the first flow space 14 , which is designed as a supply path, which is indicated here by the arrow 30 in the first flow space 14 . The cooling medium then flows from the first flow space 14 in the radial direction or radially from the inside to the outside through the transition region 22 into the second flow space 6 , where the cooling medium flows out of the second flow space in the axial direction and additionally It is driven into rotation, which is shown here by the arrow 32 in the second flow space 6 , which is designed as a return flow path.

In the electric machine, the transmission shaft 26 is structurally arranged inside the hollow rotor shaft 2 and is surrounded coaxially by the rotor shaft 2 . The stationary cooling sleeve 12 is arranged in the installation space between the transmission shaft 26 and the rotor shaft 2 . The cooling sleeve 12 here comprises two cylindrical sleeves 13 a , 13 b arranged coaxially with one another, wherein the inner first sleeve 13 a surrounds the transmission shaft 26 and forms the inner wall of the first flow space 14 . The outer sleeve 13 b here forms the outer wall of the first flow space 14 and the inner wall of the second flow space 6 . The rotor shaft 2 simultaneously forms the outer wall of the second flow space 6 .

During motor operation, the transmission shaft 26 and the rotor shaft 2 rotate relative to each other and relative to the housing 10 . In contrast, the two sleeves 13 a , 13 b of the cooling sleeve 12 are fixedly connected to the housing 10 and are therefore arranged in a stationary manner relative to the drive shaft 26 and the rotor shaft 2 .

Thus, the outer second sleeve 13b of the stationary cooling sleeve 12 separates the cooling medium flowing axially into the rotor shaft 2 through or via the first flow channel 14 designed as a supply line and through or via the first flow channel 14 designed as a return flow. The second flow space 6 of the course is radially separated from the cooling medium flowing out of the rotor shaft 2 . The flow in this case is in only one direction, here in the first direction (arrow 32 ), through the inner contour/profile of the rotor shaft 2 which forms the outer wall of the second flow space 6 . Furthermore, both sleeves 13 a , 13 b of cooling sleeve 12 are sealed both inside rotor shaft 2 and outside drive shaft 26 by seals 18 , 24 and are supported by at least one bearing device 20 inside rotor shaft 2 .

During operation of the cooling system 28 , the cooling medium is able to flow cavitation-free through the supply line as well as the return line and thus through the first channel delimited by the sleeves 13 a , 13 b of the cooling sleeve 12 as the rotor shaft 2 rotates. A flow space and a second flow space 6,14. In this case, the flow of the cooling medium into the first flow space 14 , which is designed as a supply path, is ensured by an inlet having the smallest possible first cross section. This smallest possible cross section corresponds to the diameter given by the hydraulic cross section through the electric machine. Constrictions for the cooling medium can thus be avoided without making the cross section larger than necessary.

On the contrary, the axial outflow of the cooling medium from the second flow space 6 designed as a return flow path is ensured by means of an outlet with a second cross section which is larger than the first cross section, wherein the axial outflow The cooling medium is driven to rotate by the rotating shaft. Here, the inlet is designed in the shape of a ring and is delimited by two sleeves 13a, 13b. The outlet is designed here as a ring and is delimited by the outer sleeve 13 b and the rotor shaft 2 . In the embodiment of the cooling system 28 or the electric machine, the largest possible cross section is provided for the rotating cooling medium, for example water, which flows back there (arrow 32 ). The larger the cross-section of the outlet of the rotating cooling medium through the flow space 6, the smaller the flow losses. A possible resulting pressure loss of the cooling medium is thus also reduced to a minimum. By setting the smallest possible cross-section and the largest possible cross-section and the proportional relationship between the cross-sections, the transition region 22 can be designed without air pockets.

Due to the height level between the inlet and the outlet at the rotating rotor shaft 2 , a pressure builds up for the fluid cooling medium in the cooling system 28 in a pump-like manner. This reduces the overall system-induced pressure loss of the medium in the cooling system 28 . During motor operation, a stationary and/or stationary liquid column for the cooling medium results between the two stationary sleeves 13 a , 13 b surrounding the first flow space 14 and thus the supply line. Since the rotor shaft 2 together with the second sleeve 13 b surrounds the second flow space and thus the return flow path, a rotating second fluid column for the cooling medium results.

On or in the transition region 22 between the supply line and the return flow path or between the two flow regions 6 , 14 on the bushings 13 a , 13 b or in the stationary cooling jacket 12 through the first flow region 14 The laminar inflow of the cooling medium only generates turbulence in the transition region 22 as the transition point to the rotor shaft 2 . The force of the rotating liquid column of the cooling medium in the second flow region 6 actually occurs only outside the second jacket tube 13 b of the stationary cooling jacket 12 .

Due to the coaxial configuration of the two sleeves 13 a , 13 b of the stationary cooling sleeve 12 , the axial inflow or flow direction of the cooling medium results in a very small pressure gradient and thus achieves a flow of the cooling medium between the stationary liquid column and the rotating liquid column. Cavitation-free transitions between.

Claims (9)

1. a kind of cooling system for motor, the motor includes the armature spindle (2) of power transmission shaft (26) and rotor (4), the cooling System (28) includes first sleeve (13a) and the second sleeve pipe (13b), and first sleeve (13a) is coaxially around power transmission shaft (26), and Two sleeve pipes (13b) are limited and are situated between for cooling down coaxially around first sleeve (13a), first sleeve (13a) and the second sleeve pipe (13b) First flowing space (14) of matter, armature spindle (2) is coaxially around the second sleeve pipe (13b), the second sleeve pipe (13b) and armature spindle (2) second flowing space (6) for cooling medium is limited.

2. cooling system according to claim 1, it is characterised in that the motor with the cooling system is with housing (10), power transmission shaft (26) and armature spindle (2) can rotate relative to housing (10), described two sleeve pipes (13a, 13b) and housing (10) it is fixedly connected.

3. cooling system according to claim 1 or 2, it is characterised in that the first flow channel in two flow channels (14) supply route of cooling medium can be used as, the second flow path (6) in two flow channels can be used as For the return path of cooling medium, wherein the first direction stream that cooling medium is axially directed in the operation of cooling system (28) Cross supply route, cooling medium radially flows to return path from supply route, and cooling medium is along with being axially directed to The reverse second direction being axially directed to of first direction flows through return path.

4. the cooling system according to one of the claims, it is characterised in that two flow regions (6,14) passed through Cross region (22) interconnection.

5. cooling system according to claim 4, it is characterised in that the cooling medium radially flows through transition region Domain (22).

6. the cooling system according to one of claim 3 to 5, it is characterised in that the flowing for being designed to return path is empty Between (14) coaxially around be designed to supply route the flowing space (6).

7. a kind of motor, the motor has armature spindle (2), power transmission shaft (26) and the cooling according to one of the claims System (28).

8. motor according to claim 7, it is characterised in that armature spindle (2) is being driven coaxially around power transmission shaft (26) The part of cooling system (28) is arranged between axle (26) and armature spindle (2).

9. the motor according to claim 7 or 8, it is characterised in that armature spindle (2) is designed as the carrying of rotor (4) Part and it is arranged to, makes rotor (4) be designed to drive relative to stator rotation, power transmission shaft (26) with the rotating speed of motor External device (ED) and it is configured to the rotational speed with external device (ED).